The offseason directive has already been issued, and it’s a simple one: Show up for preseason camp in shape.

Heat president Pat Riley met with reporters Wednesday and laid out the Heat’s offseason plan. It involves keeping the large majority of the team together and “improving from within” to better prepare itself for what will be a run at history — three consecutive championships. There have been only five instances in NBA history of teams winning at least three consecutive titles: Minneapolis Lakers (1951-54), Los Angeles Lakers (1999-2002), Bulls (1990-93, 1995-98), and the Celtics, who won eight in a row (1958-66).

“We need to improve,” Riley said. “Erik [Spoelstra] and I have already had two conversations about … because we’re a little older, they have to come back leaner, lighter, stronger, quicker and faster, so when you get a little bit older, you’ve got to dedicate yourself to diet and conditioning and training and becoming a better player skill-wise.”

For LeBron James, that means an offseason dedicated to the one aspect of his game that could use significant improvement, his free-throw shooting. James shot 75.3 percent from the foul line last season, which was his lowest percentage in five years.

“Our goal now is to get him up over 90 percent from the free-throw line — or he will take that on as a goal — and then Erik’s goal is to get him back to attempting 12 free throws a game,” Riley said, “if the league will ever stop allowing players to tackle him at half court.”

For other players, returning healthy and lean is the goal. Not that anyone needed reminding, but Riley pointed out how the Heat’s 2006 championship team didn’t seem to take repeating very seriously. In particular, Shaquille O’Neal was overweight, although Riley didn’t name O’Neal specifically.

“I don’t like to change that much, not when you’re winning,” said Riley, who pointed out that Bosh made five plays in the span of 20 to 30 seconds at the end Game 6 to keep the Heat alive in the NBA Finals.

When the team reconvenes in late September, Riley said he hopes 14 of the roster spots to be filled by players who were under contract in the 2013-14 season — the one exception being Juwan Howard, who likely will be replaced by a free agent.

“We’re going to cannibalize the market in August and September if we can, and hope that we can bring everybody back,” Riley said. “It’s a great team.”

The NBA Draft is Thursday night, but without a pick in the draft, the Heat isn’t expected to partake. Riley didn’t completely rule out dealing itself in for a second-round pick, but noted that “after the first 10 or 12 picks, I’m not so sure that player is out there.”

“We’ll have our top 60 players rated,” Riley said. “They will star certain players that maybe we like more than others in case we truly want to find a way to get into the draft. There are a number of situations when it comes to drafting a player and putting him in Europe possibly for the future.

“But if I ever had to do it over again, and be draft-less this year, and I gave up No. 30 to Cleveland for LeBron James, I’m OK. I’ll make that trade again, because that’s why we don’t have a pick this year.”

For the record, Riley laid out his philosophy on improving through the draft.

“I’m not interested in getting in the lottery, nor is Micky [Arison], by losing,” Riley said. “So finding young players, you can do it through free agency, trading or just finding that diamond in the rough.”

The Heat likely will look to free agency to complete its roster and at its disposal is a mini midlevel exception similar to the ones used to sign free agents Shane Battier (2011) and Ray Allen (2012). But Riley emphasized that the Heat isn’t “going to rush into anything.”

Keeping Allen, who has a player option on his contract, is a priority but Riley said Allen hasn’t informed the Heat one way or another on his next move. Allen will become a free agent July 1, at which point he can re-sign with the Heat for a 20 percent raise or part ways with the team.

“I do know that we want him back,” Riley said. “I also know that he’s a very, very smart man and that playing with LeBron and Chris Bosh and Dwyane Wade and having him on the roster and all the other players he has become very close to, I think he’ll make the wise decision. But we’ll have to wait until July 1 to see what he’s going to do.”

Notes

• Chris Andersen worked out at the Heat’s facility Wednesday but hasn’t made any public commitments to the team for next season.

“We love Chris Andersen, and we want him back,” Riley said. “He will, obviously, be informed by his agent as to all the ramifications of what’s out there as to what we can do, so until July 1, we won’t know. But we would love to have Chris back.”

• The collective bargaining agreement’s “amnesty clause” is still at the Heat’s disposal, but Riley said he’s not going to use it on Mike Miller unless he’s mandated to do so. Miller is under contract for more than $6 million next season and his contract could cost the Heat $14 million in luxury tax.

“There are time that it’s necessary to change but we don’t feel like it’s necessary to change,” said Riley, who called Miller the Robert Horry of the Heat. “Mike is healthy as he has ever been and he’s worked very hard in strengthening his back and, you watched him play, he just did not play enough.

“… Mike has sacrificed over the last three years. He is truly a great, great player. He’s not just a great shooter. He’s a great player and, so, unless I get a mandate for [amnesty] we haven’t talked about it. We just want to keep this team together.”